Apparatus and method for false twisting yarn

ABSTRACT

Disclosed is an apparatus and method for false twisting a monofilament or multifilament yarn. False twisting means are provided to impart twist to the yarn and the twisting means employs a fluid medium both to twist the yarn and control the tension of the yarn being twisted. Additionally, there may be separate means provided to supplement or more accurately control the twist being imparted to the yarn.

0 United States Patent 1191 1111 3,742,692 Bense July 3, 1973 [5 APPARATUS AND METHOD FOR FALSE 3,206,922 9/1965 Nagahara et a1. 57 34 B TWISTING YARN 3,009,309 1 l/ 1961 Breen et al 3,303,639 2/1967 Carter et al 57177.3 [75] Inventor: William M. Bense, Barrington, R.l.

, FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee' Leesona corlmmm 948,773 2/1964 Great Britain 57 34 B [22] Filed: June 1, 1971 Appl. No.: 148,326

US. Cl 57/34 HS, 57/34 B, 57/157 F [51] Int/Cl DOZg l/l6 [58] Field of Search 57/34 R, 34 B, 34 HS, S7/77.3, 157 R, 157 F, 157 TS, 157 MS; 28/1.3,1.4, 72.11, 72.12

[56] References Cited- UNlTED STATES PATENTS 2,100,588 11/1937 Claus 57/157 F 3,460,336 8/1969 Collingwood et a1 28/1.3 X 3,490,219 l/l970 Ozawa et al 57/34 B Primary Examiner-Werner H. Schroeder AttorneyShaffert and Miller [57] ABSTRACT Disclosed is an apparatus and method for false twisting a monofilament or multifilament yarn. False twisting means are provided to impart twist to the yarn and the twisting means employs a fluid medium both to twist the yarn and control the tension of the yarn being twisted. Additionally, there may be separate means provided to supplement or more accurately control the twist being imparted to the yarn.

11 Claims, 3 Drawing Figures PATENIEDJULS I975 3.742.692

mum/roe, Way/4M M. 55x55 APPARATUS AND METHOD FOR FALSE TWISTING YARN BACKGROUND OF THE INVENTION The present invention relates to an apparatus and method for false twisting yarn.

Much attention has been given by the textile art to the so-called textured synthetic yarns. One such textured synthetic yarn is commonly referred to as a torque stretch year". As is well known, these torque stretch yarns are yarns that are thermoplastic by composition (or have been rendered thermoplastic by treatment with various thermoplastic materials) and have been treated to assume a crimped or coil-like configuration. These torque stretch yarns have a certain inherent elasticity and bulkiness that distinguishes them from untreated yarns.

A common technique employed in the production of torque stretch yarn, and one that is being practiced on a widespread scale, is known as false twist texturing. This procedure involves twisting the yarn about its own axis, heating and then cooling the twisted yarn, and untwisting the yarn in a continuous operation without interruption between the individual steps. The steps of heating and then cooling the twisted yarn is often referred to as heat setting the twist.

The device employed to false twist the yarn must be capable of twisting the yarn about its own axis while the yarn is moving through the false twist device. A number of commercial devices exist that are capable of such an operation and the most common of these devices is a false twist spindle. An example of such a false twist spindle is disclosed in US. Pat. No. 3,152,436. A false twist spindle usually includes a hollow tube that is mounted for rotation about its own longitudinal axis and that has a twist trapping pin mounted transversely to the bore passing through the tube. The yarn that is to be twisted is threaded through the bore of the tube and is looped one or more times around the pin. While the yarn is being pulled through the tube, the tube is rotated about its longitudinal axis by driving means such as a movable belt. The rotation of the tube imparts twist to the yarn in the region upstream" of the tube and, while the yarn is moving through the tube, removes twist in the yarn in the region downstream of the tube. The terms upstream and downstream are used in the sense that the yarn moves through the tube from the upstream side of the tube to the downstream side of the tube.

In conventional false twist texturing machines the yarn, when in its twisted state, is subjected to heat in the region of a yarn heater and then cooled while still twisted. The yarn must remain in the twisted state until the twist is heat set into the yarn and then, after untwisting, the yarn possesses the previously discussed characteristics of torque stretch yarn.

It is important to carefully control the tension of the yarn in the region of the yarn heater and relatively low tension is desirable for optimum results because the yarn is able to uniformly twist about its own axis. Most conventional false twist texturing machines include the previously discussed false twist spindle with a twist trapping pin. Yarn feed rolls are located both upstream and downstream of the yarn heater and false twist spindle and these rolls are employed to move the yarn through the heated zone and through the spindle. By necessity, the yarn must be pulled around the twist trapping pin as it is being pulled through the false twist spindle. The moving contact of the yarn and the pin creates frictional forces that must be oversome by the pulling" ability of the downstream feed roll if the yarn is to be moved through the spindle.

Pulling the yarn around the pin of the false twist spindle requires a given force that will, of course, affect the tension of the yarn. Thus it can be seen that the use of a false twist spindle with a twist trapping pin will necessitate an increased tension on the yarn in the region of the yarn heater. As previously discussed, it is desirable to decrease rather than increase the yarn tension in the region of the yarn heater and the construction of a conventional false twist spindle works counter to the desirable result. One of the objects of my invention is to provide a false twist means that will be capable of minimizing the yarn tension while at the same time twisting the yarn. In this false twist means, both the twisting function and tension controlling function is combined into one device. Additionally, a conventional false twist spindle may be employed with the false twist means of the instant invention so that in certain applications the operator may more completely control the twist imparted to the yarn.

SUMMARY OF THE INVENTION According to the instant invention, false twist means are provided both to impart a false twist to a yarn strand and to minimize and control the tension of the yarn being so treated.

The false twist means disclosed herein is a fluid vortes generating device that includes structural means capable of directing a stream of fluid against a strand of yarn in a manner that will twist the yarn about its own axis. Additionally, the false twist means has a venturi-shaped throat positioned relative to the yarn so that the fluid stream also creates an aspirator pulling effect on the yarn in a direction toward the yarn heater.

The false twist means is a device with any convenient outer configuration or shape such as a cylinder, cube, cone or the like. The outer shape is dictated only by manufacturing convenience and the necessity to provide a convenient means to mount the false twist device on the main false twist texturing machine.

The interior configuration of the false twist means is such that the interior surfaces form a yarn passageway that extends throughout the full length of the false twist means, a fluid vortex chamber and a tangential fluid inlet to introduce fluid into the vortex chamber, a vortex guide configured in a manner to direct the incoming fluid in a helical flow path, a venturi-shaped throat, and a fluid aspirator inlet and outlet. Fluid such as air or steam is introduced into a chamber in the interior of the false twist means. A fluid guide with a helical groove or grooves formed thereon directs the fluid in a helical path within the vortex chamber. Yarn passing through the false twist means is twisted by the action of the fluid. As the fluid exits from the false twist means it passes through a venturishaped throat, the said throat also forming a portion of the yarn passageway through the false twist device. The fluid exits the device along the yarn path and in a direction toward the yarn heater. The passage of the fluid through the venturi-shaped throat creates an aspirator pulling effect on the yarn when it draws additional air through a portion of the yarn passageway. The force on the yarn strand from such a pulling effect is in a direction opposite to the direction of motion of the yarn through the false twist means. Forces are, of course, generated in the yarn as the feed rolls pull the yarn through the twisting device but the aspirator pulling effect creates forces on the yarn that are directed in the opposite direction to the feed roll forces and thereby reduce and minimize the tension in the yarn upstream from the twisting device. Additionally, the exhaust from the twisting device is directed toward the yarn cooling zone to give optimum setting conditions. This cooling is effected not only by directing a stream of fluid against the yarn but also by the natural cooling effect of an expanding volume of fluid attributable to the expansion of the fluid as it issues from the venturi-shaped throat.

As a supplemental motification of the instant invention, separate false twisting means are provided downstream of the fluid vortex device. The separate false twisting means may be any conventional type of false twist device such as a mechanical spindle or pneumatic false twist device. It may be employed as a supplemental twisting device to aid the twisting action of the fluid vortex device by governing the rate at which twist is imparted to the yarn and assuring more than uniform twist. The aspirator action of the fluid vortex device controls the tension in the yarn and the twist is imparted to the yarn by the action of the separate false twisting means and, at least to some extent, the helical motion of the fluid in the fluid vortex device.

Thus it is an object of the instant invention to provide apparatus that false twists the yarn passing therethrough, minimizes tension in the twisted yarn in the heating and cooling zones, and optimizes the yarn setting conditions by facilitating the cooling step in a torque stretch yarn producing process.

Other objects of the instant invention will be apparent to those skilled in the art from a consideration of this specification, taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION FIG. 1 illustrates several of the main elements of one station of a false twist texturing machine. These machines are large machines having many such stations along both sides, and are generally equipped with conventional false twist spindles as is well known to those of skill in the art. The particular false twist means 60 shown in FIGS. 1, 2, and 3 is in accordance with the instant invention while false twist means 70 shown in FIG. I is a conventional false twist device. Simultaneous use of both false twist devices 60 and 70 constitutes an optional modification of the instant invention. For this reason the thread line is shown broken on both sides of element 70, thereby indicating that element 70 may be eliminated.

A yarn supply source is provided with a package of thermoplastic monofilament or multi-filament yarn 11 mounted on a yarn package support 12. Yarn Y is drawn from supply package 11, passed over a yarn guide 20 and on to draw off feed rolls 30. Draw off feed rolls 30 include draw off supply roll 31 and draw off skew roll 32. Both of these feed rolls are mounted for driven rotation about their own axes but these axes are skewed relative to each other. If desired, other types of feed rolls such as pinch rolls may be employed. Yarn Y is passed around rolls 31 and 32 several times so that the several passes of yarn are separated from each other and the skewed axes of the rolls position them so that the passes will remain separated while the yarn is moving through the machine.

Yarn Y is then passed over heater surface 41 of yarn heater 40 and through guide eye 51 of fluid baffle 50. Baffle 50 may be supplied to separate the heated zone in the region of yarn heater 40 from the cooling zone that is located between heater 40 and false twist means 60, although it is noted that baffle 50 is not essential to the successful operation of the instant invention.

False twist means 60 is the next illustrated element through which yarn Y is passed. A yarn passageway is formed throughout the full length of false twist device 60 and this passageway includes aspirator exhaust passage 68, venturi-throat 66 and yarn-air bore 65.

When optional false twist device 70 is not employed yarn Y then engages a second set of feed rolls consisting of pull roll 81 and pull skew roll 82. Yarn Y engages feed rolls 80 in the same manner as described with reference to feed rolls 30. Yarn Y then proceeds to a conventional yarn take up mechanism (not shown) and, of course, a wrapped package of torque stretch yarn is wound at this location when all elements of the machine are functioning in the proper manner.

When the optional and supplemental false twist device is being used, the yarn passes through a second, separate false twist device 70 after it issues from yarnair bore 65 of false twist means 60. False twist device 70 is shown schematically in FIG. 1 as a block element but it is to be understood that it may be any conventional, well known false twist device.

False twist means 60 is shown in greater detail in FIG. 2. As previously mentioned, the exterior configuration of false twist means 60 need only be suitable for convenient attachment to the main false twist texturing machine, although manufacturing efficiencies also have a bearing on the shape. False twist means 60 may be formed of any suitable material such as metal, ceramic, wear resistant plastic and the like.

The interior configuration of false twist means 60 may best be understood with reference to FIGS. 2 and 3. Fluid inlet 61 is formed through twister housing 69 so that the innermost portion of inlet 61 is in fluid communication with the lower portion of fluid vortex chamber 62. Inlet 61 is formed so that it passes through housing 69 at an angle with the horizontal as seen in FIG. 2 and tangentially to chamber 62 as seen in FIG. 3. With such a positioning of inlet 61, the fluid passing through the inlet will be directed tangentially toward the side of vortex chamber 62 and also toward the bottom of vortex chamber 62. The outer end of inlet 61 may be countersunk or have other convenient means thereon for attachment of fluid conduit means 61A. This conduit means leads from a supply of pressurized fluid such as air or steam.

Vortex chamber 62 is generally bell shaped and completely surrounds vortex creating guide 63. This vortex creating guide projects upwardly from the bottom of vortex chamber 62 and is shaped somewhat like a beehive or a truncated cone. Formed on the exterior surface of guide 63 is a helical groove or a multiplicity of helical grooves 64 that function as a fluid stream guide. Fluid such as air or steam is introduced into chamber 62 through inlet 61 and is directed against vortex creating guide 63. The groove or grooves 64 cause the fluid to circulate in a helical spiral within chamber 62. This circulating fluid creates a fluid vortex within the confines of chamber 62 and, because groove or grooves 64 rise toward the top of guide 63, the fluid that is moving in vortex fashion is directed toward venturi throat 66. The fluid vortex first contacts the yarn in the region of venturi throat 66 and continues to engage the yarn as it progresses through the aspirator exhaust passage 68.

The yarn passing through false twist means 60 is exposed to the action of the fluid vortex on only a portion of its length because the yarn passes through yarn-air bore 65. This bore is formed throughout the full longitudinal extent of guide 63. The fluid vortex contacts the yarn before the yarn enters inner bore end 653 (FIG. 1) of yarn-air bore 65. The actual twisting of the yarn by the fluid vortex takes place between inner bore end 65B and a somewhat difficult to define upper level that is located, with reference to FIG. 2, above guide 63. As long is the fluid is moving in vortex fashion and is contacting the moving yarn it will have some twisting effect on the yarn. The upper level of the twisting region is difficult to define because the air still has some vortexlike motion when it issues from aspirator exhaust outlet 67.

The just described fluid vortex action on the yarn is responsible for the impartation of the false twist to the yarn. As is well known to whose of skill in the art, the twist that is imparted to the yarn by false twist means 60 backs up in the yarn until it reaches a feed roll such as draw off rolls 30. Thus the yarn is twisted in the region of yarnheater 40, and remains twisted in a cooled zone below heater 40 until the twist is set into the yarn. The yarn is untwisted by the time it reaches feed roll 81 and then proceeds to a yarn take up mechanism (not shown).

Exposure of the yarn to the action of the fluid vortex creates the false twist in the yarn and this is one of the features of the instant invention. False twist means 60 also has a tension controlling feature that is attributable to an aspirator-like action of the fluid stream passing through twister 60.

When a fluid such as air or steam is introduced into chamber 62, it begins to rotate and form a fluid vortex. When the fluid vortex begins to exit from chamber 62 it enters a constricted area or venturi throat 66 and then passes to an enlarged aspirator exhaust passage 68. The passage of the fluid through these portions of twister 60 creates a venturi effect that draws air from the surrounding atmosphere through yarn-air bore 65, into throat 66 and, ultimately, out aspirator exhaust outlet 67. Note that inner bore end 65B is positioned relatively closely to venturi throat 66 so that full advantage may be taken of the venturi effect. When air is drawn through yarn-air bore 65 suction forces are created that also affect the yarn that is passing through bore 65. The suction tends to pull against the yarn in a direction opposite to the direction in which the yarn is moving. In addition the combined effect of the aspirated air entering through yarn air bore 65 and the air or fluid introduced through the vortex generating supply continues to tend to pull the yarn in a direction opposite to the direction which the yarn is moving as these combined sources of air or air and fluid pass upward through the venturi. The net effect is a balancing of forces exerted on the yarn by the feed rolls that draw the yarn through its path and forces exerted on the yarn by the pull of the aspirator. The tension generated in the yarn by the aspirator effect is a function of, among other factors, fluid pressure used in the twister. As is apparent, the tension in the yarn upstream of twister 60 may be reduced to a minimum, and such a reduced tension is one of the optimum conditions for producing false twist textured yarn.

Additionally, the flow of fluid from aspirator exhaust outlet 67 is directed into the yarn cooling zone that exists between the heater 40 and the twister 60. The flow of fluid against the yarn and the natural cooling effect of an expanding volume fluid against the yarn will aid in setting the twist in the yarn. This is particularly true when air is used as the fluid medium but may also be true when the fluid is steam. All that is required is that the temperature of the fluid medium be lower than the setting temperature of the particular thermoplastic yarn being processed by the texturing machine.

It should be noted that both the location of inlet 61 relative to the wall of chamber 62 and the helix direction of groove or grooves 64 determines the hand of the twist that is imparted to the yarn. By choosing the proper tangency and helix direction, either S or Z twist may be imparted to'the yarn.

Fluid baffle 50 may, if desired, be placed between the heating zone and the cooling zone to isolate heater'40 from the effects of the fluid stream that issues from aspirator exhaust outlet 67. Baffle St) is not essential to the successful use of the instant invention but will improve the thermal efflciency of heater 40.

As aforementioned, the use of optional false twist device may be desired in certain applications. In such applications, the false twist device 70'may be used to more accurately govern the rate at which twist is imparted to the yarn and will assure a more uniform twist in the yarn.

It is noted that existing aspirators such as the one disclosed in U.S. Pat. No. 3,424,359 to Roland O. l-loule and Hans H. Richter may successfully be employed as false twist means 60. Although, the aspirator that is disclosed in U.S. Pat. No. 3,424,359 may be employed in the instant invention, the instant invention itself is not disclosed therein.

EXAMPLE A model of the twister of the instant invention has been successfully tested with 150 denier and 840 denier multifilament thermoplastic yarn. The fluid medium employed in the twister was air delivered at 35 cubic feet per minute at a pressure below PSI. It is noted that available air pressure in many textile mills is relatively low and the 80 PSI figure represents about the maximum pressure available in most mills. Thus the twister has been tested under conditions that may be reproduced in textile mills. The overfeed required in the operation of the instant invention is a function of the type of thermoplastic yarn employed, the fiber length, the twists per unit length required, the yarn heater temperature and other parameters well known to one of skill in the art. Thus the optimum overfeed,

if any, may be empirically arrived at before a particular yarn is run.

The tests shows that tension in the twisted yarn could be reduced with a concomitant optimization of the quality of the torque stretch yarn produced by the process of the instant invention.

It should be apparent that the present invention may I be embodied in other specific forms without departing from the spirit or essential attributes thereof, all of which are intended to be encompassed by the appended claims.

I claim:

1. Pneumatic yarn processing means for imparting a false twist to yarn and simultaneously exerting a tension controlling force on said yarn comprising means to impart a false twist to said yarn moving through said processing means by exposing said yarn to a helical flow of fluid and means to simultaneously control tension in said yarn moving through said processing means by exposing said yarn to aspirated fluid moving in a direction opposite to the direction in which said yarn is moving through said processing means to thereby optimize conditions for producing a false twist textured yarn.

2. Apparatus according to claim 1 including supplemental false twist means positioned downstream of said processing means.

3. Apparatus according to claim 1 wherein said yarn processing means includes means to introduce said fluid into said processing means and means to direct said fluid into a helical flow path whereby the moving fluid in said helical flow path imparts its motion to said yarn to false twist said yarn.

4. Apparatus according to claim 3 wherein said yarn processing means to control tension includes means to exhaust fluid from said yarn processing means through a region of low pressure such that additional fluid is drawn into said yarn processing means and exerts said force on said yarn as said yarn is passing through said processing means.

5. Apparatus according to claim 4 wherein said processing means includes means to direct said fluid against said yarn as said fluid exhausts from said processing means to thereby facilitate cooling of said yarn.

6. In an apparatus to process yarn including first means to draw said yarn from a yarn supply, yarn heater means providing a heated zone, a yarn cooling zone, and second means to draw said means sequentially through said heated zone and said cooling zone, the improvement comprising false twist means to impart a twist to said yarn as it passes through said zones while simultaneously controlling the tension of said yarn in said zones by exposing said yarn to aspirated fluid moving in a direction opposite to the direction in which said yarn is moving through said yarn processing machine.

7. The improvement of claim 6 wherein said means to impart a twist and said means to simultaneously control the tension are the same means.

8. The improvement of claim 7 including supplemental false twist means positioned downstream of said false twist means.

9. The improvement of claim 7 wherein said means to impart a twist and simultaneously control tension employs a moving fluid stream.

10. A method of processing a moving strand of yarn comprising the steps of passing said yarn through a false twist means, false twisting said yarn with said false twisting means and simultaneously controlling tension in said yarn with said false twisting means wherein the step of false twisting said yarn is performed by subjecting said yarn to a fluid stream moving in a helical flow path and wherein the step of controlling tension in said yarn is performed by subjecting said yarn to a fluid stream venturi effect that aspirates said yarn in a direction opposite to the direction in which the yarn is moving.

11. The method of claim 10 including the step of passing said yarn through a supplemental false twisting means located downstream of said false twist means, and operating said supplemental false twist means to impart false twist to said yarn.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,742,692 A Dated July 3, 1973 I Inventor-( M. Bense It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In.the Specification:

Column 1; line 45 downstream should have quotes around it.

Column 1, line 46 u stream and downstream should have quotes around each.

Column 1, line 48 u stream and downstream should have I quotes around each.

Column 1} line 54 heat set should have quotes around it.

Column 2, line 32 "vortes" should be vortex Column 2, line 59 "venturishaped" should be venturishaped Signed and sealed this Ath day or June 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PC4050 I uscoAAM-oc 6O376-P69 U. S. GOVERNMENTIPRINTIHG OFFICE I 9.9 0-366-31 

1. Pneumatic yarn processing means for imparting a false twist to yarn and simultaneously exerting a tension controlling force on said yarn comprising means to impart a false twist to said yarn moving through said processing means by exposing said yarn to a helical flow of fluid and means to simultaneously control tension in said yarn moving through said processing means by exposing said yarn to aspirated fluid moving in a direction opposite to the direction in which said yarn is moving through said processing means to thereby optimize conditions for producing a false twist textured yarn.
 2. Apparatus according to claim 1 including supplemental false twist means positioned downstream of said processing means.
 3. Apparatus according to claim 1 wherein said yarn processing means includes means to introduce said fluid into said processing means and means to direct said fluid into a helical flow path whereby the moving fluid in said helical flow path imparts its motion to said yarn to false twist said yarn.
 4. Apparatus according to claim 3 wherein said yarn processing means to control tension includes means to exhaust fluid from said yarn processing means through a region of low pressure such that additional fluid is drawn into said yarn processing means and exerts said force on said yarn as said yarn is passing through said processing means.
 5. Apparatus according to claim 4 wherein said processing means includes means to direct said fluid against said yarn as said fluid exhausts from said processing means to thereby facilitate cooling of said yarn.
 6. In an apparatus to process yarn including first means to draw said yarn from a yarn supply, yarn heater means providing a heated zone, a yarn cooling zone, and second means to draw said means sequentially through said heated zone and said cooling zone, the improvement comprising false twist means to impart a twist to said yarn as it passes through said zones while simultaneously controlling the tension of said yarn in said zones by exposing said yarn to aspirated fluid moving in a direction opposite to the direction in which said yarn is moving through said yarn processing machine.
 7. The improvement of claim 6 wherein said means to impart a twist and said means to simultaneously control the tension are the same means.
 8. The improvement of claim 7 including supplemental false twist means positioned downstream of said false twist means.
 9. The improvement of claim 7 wherein said means to impart a twist and simultaneously control tension employs a moving fluid stream.
 10. A method of processing a moving strand of yarn comprising the steps of passing said yarn through a false twist means, false twisting said yarn with said false twisting means and simultaneously controlling tension in said yarn with said false twisting means wherein the step of false twisting said yarn is performed by subjecting said yarn to a fluid stream moving in a helical flow path and wherein the step of controlling tension in said yarn is performed by subjecting said yarn to a fluid stream venturi effect that aspirates said yarn in a direction opposite to the direction in which the yarn is moving.
 11. The method of claim 10 including the step of passing said yarn through a supplemental false twisting means located downstream of said false twist means, and operating said supplemental false twist means to impart false twist to said yarn. 